After Esteban Santiago killed five people at the Fort Lauderdale airport on Jan. 6, reports trickled out that the Iraq War veteran had returned from his 2011 combat tour a “changed man.”

His rampage follows seven other times since 2009 that a veteran of the post-9/11 war era unleashed a shooting spree.

But that tally of events shouldn’t be seen as a trend, experts said.

Several studies and data from the U.S. Bureau of Justice Statistics show no evidence that military veterans — including those who witnessed or waged combat in Iraq and Afghanistan — are more prone to lethal violence than the general population.

The specter of the “wacko” war veteran waiting to explode — built up over generations in movies and, according to some critics, in news coverage of crimes involving military vets — very rarely becomes reality, experts said.

“Combat veterans, on the whole, are not going to be lethally violent,” said Shoba Sreenivasan, a University of Southern California psychology professor who was the lead author of a 2013 paper examining the topic.

She noted that a small segment of combat veterans may be triggered to commit violence because of their battle experiences. These individuals often have mental or emotional issues other than war-related post-traumatic stress disorder.

“There are some people — a very tiny, tiny percentage — whose combat experience creates some mental instability, along with other factors like drugs and alcohol, that then may contribute to lethal violence stateside,” Sreenivasan said.

Courtesy of the Sun-Sentinel

Esteban Santiago served in Iraq with the 1013th Engineer Company of the Puerto Rico Army National Guard. The unit deployed in April 2010 and returned 10 months later.

Esteban Santiago served in Iraq with the 1013th Engineer Company of the Puerto Rico Army National Guard. The unit deployed in April 2010 and returned 10 months later. (Courtesy of the Sun-Sentinel)

The incarceration rate for veterans is lower than for non-veterans, according to the Bureau of Justice Statistics. From 2011 to 2012, it was 855 per 100,000 veterans, versus 968 per 100,000 non-veterans.

However, a greater percentage of veterans, 64 percent, were sentenced for violent offenses, compared with 48 percent in the general population. Those crimes were more often sexual in nature than violence committed by non-vets.

As for the factor of combat experience, a quarter of veterans in prison and less than a third of jailed vets reported being part of the fighting while in the military.

Santiago served nearly a decade in the military, beginning with the Puerto Rico Army National Guard and then transferring to the Army Reserve.

A combat engineer, he was deployed to Iraq from April 2010 to February 2011.

He joined the Alaska Army National Guard in late 2014 and was living in Anchorage before he flew to Florida and opened fire with a handgun at the airport baggage terminal at midday.

While Santiago served in Iraq, two soldiers in his unit were killed by a roadside bomb. Santiago’s relatives have said he returned from that war zone a transformed person, beginning a long spiral into mental illness.

He was discharged from the Alaska National Guard in August for “unsatisfactory performance,” officials have said.

According to police records, Santiago had at least one physical altercation with his girlfriend that led to him being charged last year.

In November, he went to the FBI field office in Anchorage and reported hearing voices telling him to commit acts of violence. Santiago also claimed the U.S. government was controlling his mind, trying to make him watch videos by the jihadist group Islamic State, or ISIS.

In response to these details, some authorities are calling for stricter gun laws for the mentally ill — though experts said the great majority of mentally ill people are not violent.

Law-enforcement authorities still have not announced what Santiago’s motive was, including whether he had a diagnosed mental illness or harbored terrorist leanings.

Some conservative bloggers have promoted conversion to radical Islam as a theory, after a photo surfaced that looks like Santiago giving a hand gesture known as an ISIS salute while wearing a Middle Eastern-style scarf around his neck.

Regardless of who is brandishing the gun, mass shootings are on the rise in the United States. That’s particularly true in the past decade.

From 2000 to 2006, the yearly average was 6.4 shootings. From 2007 to 2013, the figure more than doubled, climbing to 16.4 per year, according to Harvard University’s Shorenstein Center on Media and FBI statistics.

Experts said it’s hard to accurately profile the typical mass shooter. Some are driven by ideology. Others target family members.

But some demographics are widely acknowledged. For example, the great majority of shooters are white men in their 20s to 40s.

Some experts have been critical of the way the news media has linked together cases of veterans who commit violent crimes.

For example, in a 2008 series called “War Torn,” The New York Times examined 121 cases in which Iraq or Afghanistan veterans committed or were charged with killings back at home. The series concluded that “In many of those cases, combat trauma and the stress of deployment — along with alcohol abuse, family discord and other attendant problems — appear to have set the stage for a tragedy that was part destruction, part self-destruction.”

USC’s Sreenivasan cited this series as one of the reasons she and her colleagues did their research on the link between crime and combat.

“We were concerned that Iraq and Afghanistan veterans might be erroneously considered to be more dangerous or at risk for lethal violence than anybody else,” she said.

Like it or not, deadly events involving veterans do attract considerable public attention — including Santiago’s shooting rampage.

It was 10 murder cases involving Fort Carson soldiers between 2005 and 2008 that prompted a Montana State University professor to look at whether those Colorado-based troops had been pushed too far in the battlefield. Economist D. Mark Anderson and a colleague analyzed crime in the region surrounding Fort Carson through the lens of combat deployments of its brigades.

What they found, in a study published a November 2013, was that reports of assault, murder and robbery increased when more homebound units were stationed at the base — not when infantry brigades came back from the battlefield.

The study looked at police reports from 2001 through 2009 for El Paso County, where Fort Carson is located near Colorado Springs.

“No matter how we sliced it, we did not find a consistent story for crime going up for these (returning) brigades — whether it was returning from combat really recently or maybe not recently, or your brigade suffered a lot of fatalities or not as many,” Anderson said in an interview this week.

Anderson said he was surprised by his own results. He went into the study assuming the opposite.

“Admittedly, this is not what we expected to find, but that’s what we found,” he said.

TIMELINE: POST-9/11 VETERANS AND MASS VIOLENCE

July 17, 2016: Gavin Long, 29, a former Marine and Iraq war veteran, killed three law enforcement officers in Louisiana.

July 7, 2016: Micah Johnson, 25, an Army veteran who had served in Afghanistan, ambushed and killed five white police officers in Dallas in what was described as a racially-motivated attack.

May 29, 2016: Army veteran Dionisio Garza III, 25, of Rancho Cucamonga, killed one person and injured several others in a shooting rampage at a Houston auto detail shop before being killed by a SWAT officer. Garza spent four years in the Army, receiving his discharge in 2014.

April 2, 2014: 34-year-old Army Specialist Ivan Lopez, an Iraq war veteran, being evaluated for post-traumatic stress disorder opened fire at Fort Hood, killing three people and wounding 16 before killing himself.

Sept. 17, 2013: Aaron Alexis, 34, a civilian defense contractor, went on a shooting rampage inside a building at the heavily secured Washington Navy Yard, killing 12 people before he was slain in a running shootout with police. Alexis served as a full-time Navy reservist between 2007 and 2011.

March 11, 2012: Sixteen Afghan villagers, including nine children, were killed during a predawn attack. U.S. Army Staff Sgt. Robert Bales pleaded guilty in a deal to avoid the death penalty was sentenced Aug. 23, 2013 to life in prison with no chance of parole. Bales never explained why he armed himself with a 9 mm pistol and an M-4 rifle and left his post on the killing mission.

Nov. 5, 2009: Maj. Nidal Malik Hasan, 39, a U.S. Army psychiatrist, killed 13 when he went on a rampage at Fort Hood, Texas. Hasan, 39, was convicted in August for killing 13 people. He told the court he had “changed sides” and was performing jihad.

Retired school teacher Tom Rice of Coronado did a tandem jump in France as part of the annual D-Day remembrance.

Retired school teacher Tom Rice of Coronado did a tandem jump in France as part of the annual D-Day remembrance.

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Retired school teacher Tom Rice of Coronado did a tandem jump in France as part of the annual D-Day remembrance.

Retired school teacher Tom Rice of Coronado did a tandem jump in France as part of the annual D-Day remembrance.

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Vietnam War veterans use Memorial Day weekend to read out loud the names of San Diegans killed in the Vietnam War and still missing.

Vietnam War veterans use Memorial Day weekend to read out loud the names of San Diegans killed in the Vietnam War and still missing.

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The restored B-17 Flying Fortress was a tough act for anyone to follow but Donald Foulks was up to the task. As a 22-year-old bombardier, he was imprisoned in Nazi Germany's infamous Stalag Luft III, site of "The Great Escape."

The restored B-17 Flying Fortress was a tough act for anyone to follow but Donald Foulks was up to the task. As a 22-year-old bombardier, he was imprisoned in Nazi Germany's infamous Stalag Luft III, site of "The Great Escape."

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The littoral combat ship Omaha arrived in San Diego on Friday and will be commissioned on Feb. 3.

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